We are evaluating cognitive function in the oldest members of the ORPRC's Primate Aging Colony, six males and one female ranging from 28 to 32 years of age, in comparison with younger adults which are 8 to13 years old. In collaboration with Drs. Mark Moss and Douglas Rosene of the Boston University's Laboratory of the Neurobiology of Aging, a cognitive assessment battery has been designed and testing methods have been standardized across the two sites. The battery includes the delayed non-matching to sample task, a classic test of visual recognition memory, and the delayed recognition span task, which measures memory capacity. We also plan to construct an automated system to administer an attentional set-shifting task which is dependent on frontal lobe function and is selectively impaired in human aging and dementia. In addition we are evaluating other aspects of behavior, including behavioral reactivity as assessed with a test designed for evaluating effects of limbic s ystem damage, and motor deficits using a primate adaptation of a clinical Parkinson's symptoms rating scale. In preliminary results for the delayed non-matching to sample task, the older animals all have required several hundred more trials to achieve criterion performance (90% correct over 100 trials) than any of the younger group. In the behavioral reactivity task, no differences were found in the two age groups' responses to a variety of objects and social stimuli. Thus, impaired performance in the delayed non-matching to sample task is not related to negative responses to the variety of objects used as stimuli in the task. These ongoing studies will allow us to (1) assess cognitive and behavioral changes in a valuable group of primates of advanced age, and (2) relate these behavioral changes to quantitative measures of brain atrophy obtained by magnetic resonance imaging, measures of endocrine status, and neuropathological and molecular biological changes which will be evaluated at the end of their lifespan. FUNDING Nonfederal institutional funds PUBLICATIONS None